As of some unknown number of days ago, the emails from meta have a really really thin font, which makes reading on my phone extremely difficult.
This is how emails look in Gmail app:
This is how emails look in my normal email client - AquaMail:
On the other hand, this is how emails look on a different discourse instance which is not yet updated to latest tests-passed:
I find the font here much more pleasing to read, as it has better contrast.
(Please ignore the extremely large font size, I tried to increase the font, hoping that something might change).
On the other hand, on the desktop I found no issues with the font, only on mobile:
Using a OnePlus 5t